JPS6063329A - Treatment of dust - Google Patents

Abstract

PURPOSE:To remove incorporated heavy metals and to separate and recover an alkali metallic salt by subjecting the aq. soln. obtained by treatment of the upper layer part having low specific gravity with water to pH adjustment and chelating treatment, wherein said part is taken out by melting dust produced from a waste incinerator on the inside of a furnace. CONSTITUTION:The dust produced from an incinerator of municipal refuse and other wastes is supplied to a furnace 1 made of a refractory from an inlet 2, and melted by combustion of gas out of a nozzle 4 to make slag 9. The slag 9 is kept molten by conducting electricity across two electrodes 5 in the slag 9, and the upper part having low specific gravity which is composed essentially of alkali metallic salts such as NaCl and KCl is taken out from the upper discharge port 6 for the slag. The incorporated alkali metallic salts are eluted by pouring said part in water, thereafter pH is adjusted to 9-12 by addition of alkali such as NaOH and the heavy metals incorporated in the aq. soln. are precipitated as hydroxide or the like by addition of chelating agent and separated. The alkali metallic salts are separated and recovered by cooling the remaining liquid.

Description

[Detailed description of the invention] The present invention relates to a dust processing method.

For more details, please refer to the waste incinerator 1, which separates and collects metal salts from the dust generated from municipal waste incinerators. l! X1! l! It is related to the method.

Various wastes such as municipal garbage, sewage sludge, treated wastewater discharged from mines, etc. are incinerated in incinerators and 11 furnaces, and the resulting incineration ash has conventionally been disposed of in landfills. However, it is difficult to secure land for landfill, and the harmful heavy metals contained in it are leached into the ground. Due to the risk of contaminating the Tachikawa land area and causing secondary pollution, recent methods have been introduced, such as melting and solidification using electric arc furnaces or direct current melting furnaces using base metals. It's been fabricated. The waste is burned in the above incinerator, and the generated powder a<dust) is released into the atmosphere.
Since it stains with IQ, it is captured by various types of dust collectors such as wet dust collectors, electric dust collectors, and bag filters. -Contains water-soluble salts such as NaC, K C, and Ca o, si 02 , AAz O
It contains water-insoluble oxides such as a, F(i20'a), and heavy metals such as ΔS, Cr, 7n, Cd, Pb, and H(], and these heavy metals are generally hal- There are many water-soluble forms of phosphorus, such as chloride compounds or Iii!I salts.Therefore, if this dust is buried in the ground as it is, there is a risk that heavy metals will be leached into the ground. 1', the same method as incineration ash is used to melt and solidify the waste. After several inspections, the dust was directly energized.
,'＋! ! When melting is carried out in a processing furnace, the upper and lower layers of the slag produced have different compositions, and are produced separately.
: We filed a patent application for the idea that by harvesting, it is possible to use each material effectively according to its characteristics, and that heavy metals can be rendered harmless (patent application Sho Ei6-128637)
.

This type of separated waste has a3° (-1 soil layer composition is Na
It is a component mainly composed of alkali metal salts like C9-1KO, and the composition of the lower layer is ca o, si 02, A 2
The slag consists mainly of oxides such as 0B, Fe, 20B, etc., but it is inevitable that a small amount of detoxified heavy metals will be mixed in each slag. is solidified and recycled into fine particles such as sand,
tsu! ! (Although the mixture of poisonous heavy metals is not a problem, the upper layer of molten slag contains components such as NaC and KC. The present inventors have extracted alkali metals from the dust generated from waste incinerators, which are useful for the production of secondary products such as Na0 and KC, from which small metals have been removed. As a result of investigation regarding the dust processing method for separating and recovering salts, it was found that among the sludge separated into the two layers mentioned above, the sludge aqueous solution in the upper layer was PL-1.
49 found that it is possible to separate and recover alkali metal salts at high concentrations by adjusting, cleaning, and treating heavy metals by sedimentation or adsorption, and by utilizing the difference in solubility.

Therefore, in the present invention, dust generated from a waste incinerator is treated in a direct current melting furnace equipped with upper and lower slag discharge ports, and the generated slag is treated with a water-soluble alkali metal salt. The upper layer slag is mainly composed of oxides that are poorly soluble in water, and the lower layer slag is mainly composed of oxides that are poorly soluble in water.The aqueous solution of the upper layer slag is
The gist of this is a dust processing method characterized by adjusting the dust to H9 to H12, processing it to Kirey-1 to remove the contained heavy metals, and then cooling and separating and recovering the precipitated alkali metal salts. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on drawings showing an example of an apparatus to which the present invention is applied.

Figure 1 is an n-side schematic diagram of a direct current melting furnace, in which the furnace body is made of 3i 02-AizOa with a high content of ZrO2, for example.
-7r 02 series fire resistance 4J! 1'! It is constructed in a hermetically sealed manner, including an inlet 2 for the dust generated during the burning of waste, a trachea 3, a heating device for the initial melting of the injected dust, e.g. Nozzle 4, horizontally movable electrode 5.5, upper slag discharge port 6,
A lower slag discharge lower is provided. Furthermore, this 2
The two discharge ports 6.7 are provided with as much head difference as possible within the allowable range of the furnace structure. An alternating current is passed through the electrode 5.5 through the voltage regulating power source 1 to the lance 8, and the dust introduced from the dust inlet 2 is transferred to the fuel gas injection nozzle 4.
The generated molten slag 9 itself becomes a conductor, generates Joule heat, and maintains the molten state by internal heating. A typical example of the shrine 11 is a molybdenum electrode, and other examples include graphite, iron, tin oxide, and tungsten electrodes.

Therefore, in the present invention, the dust generated when incinerating waste such as municipal garbage, sewage sludge, mine and industrial wastewater, etc., especially the dust generated from the fflL bundled incinerator containing a large amount of salts, can be directly treated as described above. When melting is performed using a processing furnace capable of non-oxidation melting such as an electric melting processing furnace, the composition of the upper layer of the generated slag is Na C01KC1 in the dust.
Mainly composed of water-soluble alkali metal salts, with a specific gravity of 1
．． 9 to 2.1, and the lower layer is Ca 01 Si 02
, △! 1203, based on the knowledge that the water of FQzoa mainly contains sparingly soluble components and has a specific gravity of 2.5 to 2.7, each of them is slaged separately from the outlet of the furnace body, which is provided in two stages, upper and lower. This makes it easier to carry out the 51! process for effective utilization of slag, which will be described later.

To treat dust generated in a waste incinerator using the direct current melting furnace shown in Fig. 1, the dust is introduced into the furnace body through the dust inlet 2, and the initial Gas sound! 4J nozzle 4 heats the garlic gas to melt it and form molten slag 9. The temperature of the slag 9 in this case depends on the type of dust introduced, but is approximately 1200 to 1
The temperature range is 350°C. At the time of A, take it to the furnace body
An electric current 4Ii5.5 is immersed in the M house in advance and an alternating current is passed through it, and the molten state is maintained by the Joule heat generated by using it as a conductor. The current at this time is equal to the sacrifice tT for the input das 1, but i13 is about 700 to 1200
KW/1. (Subject 1! I! Thing) Category 1! II. Note that 10 is a covering layer in an unmolten state of das i~ which is sequentially introduced (LIT).

Next, the upper layer of the generated slag 9 is discharged from the slag outlet 6 into the furnace main body and discharged into a water-filled bit. It elutes in water. Also, CaO1AizOa of slag 9
, Si 02, Fe 20B, etc. in water! ! The lower layer, which mainly contains soluble components, is extracted from the slag discharge lower located at the lower position of the two discharge ports provided in the furnace body, and is transported and solidified together with the detoxified specie Iil. .

Next, Figure 2 shows the flow for separating and recovering alkali metal salts such as NaC&, KCl, etc., which are the main components, from the molten slag in the upper layer, which is separated and extracted in a processing furnace (1 = slag is separated in a processing furnace) as shown in Figure 1. This is a diagram showing the

Direct current melting process 1 in Figure 1! I! Furnace upper discharge port 6
The slag extracted from the slag passes through a line 11 and is injected into pits 1 to 13 filled with dry water 12 heated to 80 to -90°C by waste heat generated from a waste incinerator, for example. be done.

Then, add an alkali such as NaOH from line 14 to adjust P)I to 9 to 12, and also from line 1
From 5 onwards, a chelating agent was added and a trace amount of 1 was added to the slag solution.
The heavy metals that are present in the form of hydroxides and the form of chelate viscosity C) are filtered through the first 1 (Y).The slag solution containing small metal precipitates is filtered through the pump 16 and the urea line 1. (Move to container 18)
Sushikil! The filtered sap is then sent to a cooling tank 19 equipped with, for example, cold water or brine cooling piping, and cooled to about 20 Tl or less. Of the NaC and KCl contained in the filtration mother liquor, K C and Q have lower solubility than NaC at this temperature and will precipitate. J.
NaCl and KCl are separated from the saturated filtration mother liquor, approximately 90%
KCl crystal 21 that does not contain heavy metals and has a high purity
Collect. In addition, NaC and K C do not contain heavy metals.
1 of saturated filtered mother liquor is transferred via line 22 by pump 23, heated in heater 24 and recycled to bit 13. Also, N80-rich crystals are collected from the branch pipe 22a and evaporated using waste heat generated from, for example, a waste treatment furnace and contain KCl. Examples of chelating agents used in the above separation operation include Miyoshi Yushi Co., Ltd., 19
The product name is "Koboflock L-1". Incidentally, instead of adding the chelate ion agent from the line 15, a chelate ion resin filtration layer may be provided in the filter 18 to adsorb and filter heavy metals in the molten slag. For example, the chelate resin layer may be manufactured by Sumitomo Chemical under the trade name [Sumichelate MC].
-304 is mentioned.

The present invention is to process the dust generated from the above-mentioned J: Uni, Haitomono-yaki N furnace in a direct energized melting furnace equipped with upper and lower slag discharge ports, and convert the generated sludge into water. The slag is separated into an upper layer slag mainly consisting of soluble alkali metal salts and a lower layer slag mainly consisting of soluble oxides, and the aqueous solution of the upper layer slag is chelated to remove heavy metals and produce fertilizer. N is useful as a raw material for refrigerants used in the production of electrolytic caustic soda, etc.
This is a dust processing method that separates and recovers alkali metal salts such as aCl and KCl with high purity, and it makes a great contribution to waste treatment and recycling projects.

Example 1 Dust generated from a municipal waste incinerator was captured using an electric dust collector to obtain dust having the composition shown in Table 1.

Table 1 Note 1: The 0 in the margin is the landfill standard value.

Note 2 The elution test for heavy metals is in accordance with the Environment Agency Notification No. 14.

Next, sample 1 in Table 1 was treated with molten R1 in a direct energized melting furnace (not shown in Figure 1), and the molten slag 1jl in the lower row was
Upper layer slag Δoni and lower layer slag il discharged from outlet 6
Table 2 shows the results of investigating the composition of the lower layer of slag discharged from the +l outlet.

The slag in the upper layer from the Ui fruits shown in Table 2 and above contains water-resistant components (Na
C, Q,, K, 0 sentences) are the main components, whereas the slag in the lower layer contains 11 components lacking in water (Ca○, ΔT203, S
i 02, FO20B, etc.) is clearly the subject C. In addition, it can be seen that the polymerization group; j1 in sample Od.

Next, the upper layer of slag A in Table 2 was heated to 90°C as shown in the flow diagram shown in Figure 2.
1'l'l' in pitch 1 to 13 that filled 00 standing
L/, add NaOH from rest line 14 -c M % 1] 1
1 was adjusted to 9 to 12, and the processing agent EvoFloc L-1 was added to line 15j; Liquire-1. Generated: car money l
The treated liquid containing precipitates of ip, etc. is transferred to the pump 1G and the dust line 17 to the IM'r'da filter 18 for filtration, and for filtration, the liquid is transferred to the cooling layer 19 and cooled to about 25°C.
L,,1〈C vertical crystals were precipitated. Precipitated KCl2
1 is separated in a separator 20, and the filtered mother liquor saturated with NaC and KC is transferred via a line 22 by a pump 23, heated by a heater 24, and circulated to the pit 13. In addition, a portion of the Na (4-based crystals) is evaporated in an evaporator (not shown) through a branch pipe 22a.

The obtained KO sentence and NaC stand were investigated (the results are shown in Table 3). For comparison 1, in the flow diagram shown in FIG. 2, the slag solution of Pi1-13 without addition of Na0l- ) and the results of an investigation on the recovered NaC crystals are also listed.

Table 3 As is clear from the results in Table 3, the metal salts recovered from the molten slag solutions treated with Kire-1, such as K C, NaC9, etc., contain small metals (Jl'ii). However, it could be used satisfactorily for KCl fertilizer and electrolytic Na0l-I production.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing an example of a direct) m type melting furnace to which the method of the present invention is applied, and Fig.
FIG. 2 is a flowchart for recovering and separating alkali metal salts from the upper layer of slag. 1... Fireproof U)'ul 2... Dust inlet 3.
...Ventilation pipe 4...Fuel gas injection nozzle 5...Electrode 6.7...IJI output 1:18...Power transformer for voltage adjustment 9...Slag 10... Covering layer 11... Line 12... Hot water 13... Pi1- 14.15... Line 16...
・Pump 17...Line 18...Filter 1...Cooling IQ 20...1 minute
i11f device 21...K O standing crystal 22...line 23...pump 2/l...heater agent Patent attorney Tsutomu Adachi and one other person Figure 1Z Figure 2

Claims (1)

[Scope of Claims] 1. Dust generated from the Abandoned Tomono Yakino JI furnace is treated in a direct energized melting furnace equipped with two tiers of Juo and one outlet for slag, and the generated slag is Soluble 1 (1 of 7/T1 (soluble oxide) in water and the upper layer slag mainly composed of alkali metal salts,
1) IJ
Note 1 = "eJ (D aqueous solution of slag P 149~12 nill!l T+', shi, 4 elm-1 ~ place 1!l L
A dust processing method characterized by removing the heavy metals contained in the F layer and recovering the alkali metal salts that precipitate by cooling. The slag is composed mainly of NaC or K 0 and is soluble in water, while the lower slag is composed mainly of Ca o, AA20a, l:Te203.5102 and is soluble in water. The method for treating dust according to item 1, which is an oxide of The dust processing method according to claim 1 or 2, which is one of adsorption separation methods.